Galvanizing technique for wire and the like

ABSTRACT

A METHOD AND APPARATUS FOR EVENLY AND UNIFORMLY GALVANIZING WIRE, STRIP STEEL AND THE LIKE. A DESCALED, DRY WIRE OR THE LIKE IS PASSED VERTICALLY AND UPWARDLY THROUGH A TRANSVERSELY FLOWING STREAM OF MOLTEN ZINC WITHOUT TOUCHING ANYTHING SOLID WHILE THE ZINC AND THE WIRE ARE   IN AN OXYGEN FREE ATMOSPHERE. THE SO COATED WIRE IS PREFERABLY QUENCHED IN A FLOWING WATER BATH.

J. L. HERMAN 3,809,570

GALVANIZING TECHNIQUE FOR WIRE AND THE LIKE May 7, 1974 Filed May 17, 1973 United States Patent M 17 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for evenly and uniformly galvanizing wire, strip steel and the like. A descaled, dry wire or the like is passed vertically and upwardly through a transversely flowing stream of molten, zinc without touching anything solid while the zinc and the wire are in an oxygen free atmosphere. The so coated wire is preferablyquenched in a flowing water bath.

BACKGROUND OF THE INVENTION In the of galvanizing iron containing objects, it has been difficult to produce uniform, even coats of zinc thereon by immersing such objects in a bath of molten zinc. The protective coating normally consists of several layers, with thoseclo'se'st'to the oasis metal being composed of iron-zinc'compounds, and these, in turn, are covered by anoutr layer consisting almostentirely of zinc. These layers have a complex" structure and the properties of a coating c'anbe greatly affected by relatively small difierences in coating composition, bath temperature, immersion' time, immersion procedure, cooling rate, and the like.

In the case of Wire, strip steel, and the like, as those skilled in the art appreciate, galvanized coatings are subject to severe variations in thickness, uniformity and the like not only from one lengthwise position to another,

3,809,570 Patented May 7,, 197;

by this invention, the zinc is replaced andreplenished every few hours, instead of every few weeks as is done contemporarily. Another reason is that, in this invention, Wire or the like being galvanized is contacted with molten zinc for only a very short interval of time. A third and primary reason is that in this invention the wire, or the like being galvanizedas well as the molten zinc are maintained together substantially in the absence of oxygen. Skimmings may be reduced or even avoided.

Further, by the present invention, the cost of galvanizing wire and the like may be reduced greatly compared to the prior art because of the thin, uniform, even coatings producible by the present invention with or without gas wiping or the like, and because of the small quantities of molten zinc needed during galvanizing, thereby avoiding the waste of zinc'associated with known wire galvanizing but .also even from one side of a wire to another circumprior art because'of the difliculty and general inability to produce, even zinc coatings thereon.

' Such zinc coating variations appear to be inherently methods.

.Further by the present invention, since wires and the like are contacted with hot, melted molten zinc for only brief intervals of time, by-product formation and contamination are cut down. I

Further, by the present invention, close, precise, uniform process controls and conditions, especially zinc temperatures, can be maintained, which can be rapidly varied, if desired or needed, thereby to regulate molten zinc viscosity and other process variables.

Further, by the present invention, one may employ advantageous features of slight positive, non-oxidative gas pressures in the region of the galvanizing operation using, for example, natural or city gas, if desired.

Formation of oxygen skins may be substantially reduced or even eliminated and dross that is made from tons of wire passing through metal baths may be virtually eliminated as wires pass through a small stream of zinc as taught by this invention rather than being drawn through long pots as done in the prior art.

The molten zinc used for galvanizing in this invention may be homogenized and continuously mixed to keep the molten zinc in a uniform condition. Such homogenization and mixing may be achieved by motor driven propellers or the like and the resulting churning movement of the ,molte n zinc which can blend the molten zinc into a smooth associated with prior art galvanizing techniques which.

BRIEF SUMMARY oF THB'I VENTION coating of zinc that can have a uniform viscosity that will flow evenly.

Other and further objects, purposes, advantages, utilitiesQand features will be apparent to those skilled in the The present'invention relates to the galvanizing of iron. A

or steel Wire, strip steel, and other galvanizable. Wire-like material and moreespec'ially to the conditions employed to apply the molten zinc to such materials and to, the subsequent processing thereof. By the present invention the rusting and contamination problems caused by oxidation are eliminate'db'ecause the present technique of galvanizing is practiced substantially in the absence of oxygen, and in a non-oxidizingenvironrnent.

Further by the presentinvention, steel wire or other such galvanizable filamentous material is upwardly fed through a galvanizing stream of'zinc'without contacting anything other than molten zinc while the coating'on the wireis in a molten state. 1

Further, by the present invention, one may keep the molten zinc'in the mother pot freer of deleterious substances such as dross, skimrnings, oxides, and the like,- and art from a reading of the present specification, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic, side elevational, partially sectionalized view of one embodiment of apparatus adapted for galvanizing galvanizable metallic material in a wirelike form, and also to an apparatus for practicing such process.

The term wire-like or even wire is used herein as a matter of convenience as a generic term inclusive of wires, cables, strips of relatvely narrow width filaments, fibers, long strands and the like.

In the process of this invention, one passes preferably substantiallycompletely descaled, preferably substantially completely dry wire of galvanizable, preferably iron containing material vertically through a generally transversely tflowing (relative to the direction of wire movement) stream of molten zinc while maintaining the zinc and wire in a substantially oxygen free atmosphere without the wire touching anything. Thereafter, one maintains the so-coated wire in such vertical position in the oxygen free atmosphere until 'the resulting coating-of zinc-on the wire has solidified.

Preferably, after the wire has passed through the stream of molten zinc, and while the 'resulting-so-coated wire is in its vertical position, and also while the wire remains in its substantially oxygen free atmosphere, the so-coated wire is passed upwardly through a water bath. The temperature of the water bath and the residence time of such so-coated wire in such bath are chosen so that the resulting coating of zinc on such wire has cooled and set before the-so-coated wire emerges from the bath. The so-coated and cooled wire may be permitted to enter an oxygen atmosphere after leaving such water bath. Preferably, the water bath is in the form of a stream of water which flows in a direction generally transversely to such vertically oriented, coated wire..

Typically, the thickness measured vertically through the flowing stream of molten zinc at the point where the wire passes therethrough is not more than about two inches in vertical thickness. Preferably this thickness is not more than about one inch at such place though larger and smaller such thicknesses can readily be used without departing from this invention, as those skilled in the art will appreciate. The wire vertically travels through such flowing stream of molten zinc at rates: typically in the range of from about 10 to- 30 feet per minute, although those skilled in the art will appreciate that slower and faster travel rates can be used without departing from the spirit and scope of this invention. A presently preferred preference is to use travel rates in the rangeof from about 15 to 25 feet per minute. a

The flowing stream of molten zinc is preferably maintained during a galvanizing operation at a substantially constant temperature when the wire passes therethrough. Typical stream temperatures fall in the range of from about 800 to 900 F. 7

Typically, wires coated in accordance with the teachings of the present invention have coating weights of zinc of not more than about 2 ounces per square foot of coated wire surface and at a maximum are typical, but; lower or higher such weights may sometimes be desired. In terms of coating thickness, such a typical coated and cooled wire has a zinc coating which typically ranges from about 0.05 to 0.0001 inch. It is preferred to use the present invention to prepare wires which are coatedwith a relatively thin layer of zinc; thus, one class of preferred coating thicknesses range from about 0.0001 to 0.001 inch. Preferred galvanizable metallic materials include iron and iron alloys especially steel, of course. One preferredclass of wire-like forms comprises steel containing not; more than about 0.4 weight percent carbon, as those skilled in the art will appreciate.

Before being subjected to a galvanizing operation in accordance with the teachings of this invention, a wire should preferably be free of oil, grease, drawing lubricants, mill scale, and other surface contaminants,as those skilled in the art will appreciate. Any conventional degreasing and/or acid pickling operation may be used as desired by one skilled in the art before subjecting a wire to a galvanizing operation in accordance with the teachings of this invention.

For example, to clean a wire, one or more of several conventional methods may be used, including vapor degreasing, solvent cleaning, alkaline cleaning, and emulsion cleaning. Aqueous solutions of sulfuric acid (or to "a lesser extent, of hydrochloric acid) are commonly used to re-' move mill scale and rust in a so-called acid pickling operation prior to galvanizing. The concentration of s'ul-' furic or hydrochloric acid pickling baths normally ranges from about 6 /2 to 13 /2 ounces of sulfuric acid or hydrochloric acid per gallon of water. Preferably, the pickling solution is used hot at a temperature in the range typically of from about 140 to 175 E, th gh it is p ferred to usehydrochloric acid solutions at about room temperature '5 harmful. Within the above indicated normal galvanizing- (about 75 to F.) to avoid dangerous fuming.

After degreasing and pickling, it is preferred to subject a wire to a thorough rinsingoperation to remove from the wire iron salts, finely divided iron and possibly other contaminants. To be as effective as possible, the rinsing operation may be combined with a scrubbing action, as those skilled in the art will appreciate.

Any small amounts of impurities remaining on a wire after degreasing, pickling, water rinsing and other cleaning procedures maybe removed, as those skilled in the art will appreciate, using a flux. Although so-called wet and dry galvanizing requires fluxes and employs essentially the same flux materials, the composition of the flux is partly dependent on a specific galvanizing method employed. Here, if a flux is employed, it is preferred to apply the flux to the surface of the wire before such is immersed in molten zinc.

After such preparatory procedures, a wire is dried substantially completely by being heated to a temperature in the range of from about 250 to 400 F., although those skilled in the art will appreciate that lower and higher temperatures may be used in a drying operation if desired. If a filament has been subjected to a flux, during drying, surface chlorides and oxides are taken up by reaction with a portion of the flux; the remaining flux then contributes to the wetting action when the filament is passed through the molten zinc bath.

Any grade of zinc conventionallyused in galvanizing such as zines covered in ASTM B6 can be used in galvanizing. One preferred type of zinc is the so-called prime Western Zinc which reportedly contains about the highest commercially allowable percentage (1.68%) of lead and iron. As those skilled in the art will appreciate, the purity of the zinc used in galvanizing has an effect on the bending properties of the product coatings. In general, particularly when coatings with good bending properties are to be produced in accordance with the practice of the present invention, a high purity zinc is preferred; for this purpose azinc grade such'as has been conventionally used for many years in producing high quality galvanized wire may be employed such as the for purposes of the present invention, usually in the range of from about 800 to 900 F. Higher temperatures may be used, such as temperatures of above about 900 F. or. higher but at such temperatures the solution rate of iron and steel in zinc is quite rapid, and the effects of these temperatures on a wire being galvanized may be temperature range, an increase in temperature can (a) allow more complete drainage of zinc from the 'galvanized wire (b) increase the fluidity of the molten zinc,

and (c) heat the wire to a higher'temperature as it passes through the zinc stream. Thus, temperature regulation may be used to control galvanizing quality.

An increase in bath fluidity generally improves the drainage and is desirable provided the bath temperature does'not'exceed the normal operating range. However,

as thoseskilled in the art will appreciate, an increase in bath'temperature produces a sharper temperature gradient from the surface to the center of thewire, and higher wire temperatures may also extend the time required for the zinc to solidify after the wire is withdrawn from the bath.

A preferred operating procedure when practicing the present invention is to determine an optimum bath temperature for a given filament to be galvanized by starting at a relatively low temperature in the normal range (about 800 to 900 F.) and raising the temperature in increments of approximately 5 degrees Fahrenheit until the most satisfactory galvanizing results are obtained. Those skilled in the art'will appreciate that modifications in this approach, such as preheating the workpiece, 'or adding small amounts of aluminum to the bath. to increase fluidity, may also be employed.

In order to avoid and/or substantially minimize corrosion and contamination problems, the region around the flowing bath of molten zinc used to coat a wire in accordance with the teachings of the present invention is maintained in a substantially oxygen free gaseous environment. While such an environment may be achieved by using reduced pressure or vacuum conditions in such region, I presently prefer to employ a substantially nonoxidizing or substantially oxygen free gaseous environment in such region and to maintain the pressure in such region at a level slightly above atmospheric such as is taught, .for example, in my earlier patents in this art; see Herman US. Pat. 2,166,251 and US. Pat. 2,166,250. Conveniently, a chamber surrounding the flowing stream of zinc is filled with such an oxygen free gas and the gas is allowed to escape from the chamber through the wire entry and 'exit ports therein. Suitable gas mixtures for this purpose include nitrogen, helium, gaseous halogenated hydrocarbons, gaseous lower-aliphatic hydrocarbons (such as the mixtures commercially available under such names and trade designations as Natural or City Gas), and the like. When, for example, the last indicated gas is used, atevery opening from the galvanizing chamber, gas escapes and may be burned by igniting the same at such openings. Preferably, about a wire, the flame passes outwardly and upwardly, and envelops the wire, and so adds to and aids in, providing an oxygen free environment. v

r The residence time of a wire being galvanized in the flowing stream of molten zinc may be varied. Such timing. is to some extent dependent. onease of handling, processing conditions, nature of the wire, etc., and -an optimum procession, immersion time-for eachtype of wire necessarily should be established by' trial. general, duration of immersion in a flowinglstream of molten zinc for a given wire typically falls in'the range of from about 0.001 of a second to seconds, although longer and shorter times as desired may be employed as those skilled in the art will appreciate. A reaction between clean steel being galvanized and molten zinc contacting same may proceed relatively rapidly at first resulting in the production of an alloy layer which can continue to grow at a decreased rate the longer the 'zinc in contact with the wireremains in a molten condition.

After a coated wire is withdrawn from the flowing bath of moltenzinc, it continues to move vertically, as indicated. Preferably, before the so-coated wire is permitted. to re-enter an oxygen containing atmosphere, the molten zinc is solidified by cooling and setting. For purposes of the present invention, it is convenient and preferred to pass a coated filament with molten zinc thereon through a water bath, which such wire-like form is in such oxygen free atmosphere as indicated, before the wire reaches an oxygen atmosphere.

The temperature of the water bath and the residence time of such so-coated wire-like form in said bath 'are such that the resulting coating of zinc on such wire-like form has cooled and set. Preferably, a jet of Water is permitted to flow onto or against and around a coated wire or the like generally transversely of the coated wire, the water jet beingpermitted to be located adjacent the exit port of the'chamber wherein the galvanizing is being accomplished. Water reaching the coating has direct contact and influence thereon in setting and fixing the coating in a manner such that the zinc is solidified completely before passing through the water bath and on into an oxygen containing atmosphere. A plurality of streams of 'water may be thrown against the wire as it moves vertically therethrough, but in general, it has been found that a single jet is suflicient.

In a preferred method of practicing the present invention, a wire is first passed through a pickling bath to remove substantially all scale therefrom. Next, the so-pickled wire is passed through a drying zone wherein the so-pickled wire is subjected to elevated temperatures for a time suflicient to substantially completed dry the wire. Thereafter, the so-dried wire is passed vertically upwardly through a generally transversely flowing stream of molten zinc while simultaneously maintaining the wire in a vertical position and maintaining the molten zinc and said wire in a substantially oxygen free atmosphere. Finally, the socoated wire, while still in said vertical position and while still in the substantially oxygen free atmosphere, is passed upwardly through a water bath, the temperature of the bath and the residence time of the wire in the bath being such that the zinc coating is cooled below its melting point while in the bath. Several wires may be coated simultaneously.

In addition to a pickling, a wire is preferably subjected to a degreasing operation which precedes the pickling. Optionally, if desired, a wire may be subjected to a fluxing operation after a pickling operation. Optionally, if desired, a water rinsing or washing, including scrubbing, can take place between the pickling and the fluxing operations and before the drying operation.

After traversing upwardly through a first flowing stream of moltenzinc and while still in a vertical position in an oxygen free atmosphere, a wire may be passed through a second or further separate flowing stream of molten zine arranged in layered or storied fashion one above the other over the vertically moving path of the wire.

.Preferably, after a coating operation wherein a wire is subjected to passage through one or more flowing streams of molten zinc, the resulting wire while still upwardly moving andwith the zinc maintained in a molten condition is subjected to theaction, ofa gas-wipe, the gas being substan,- tiallyfree of oxygen pref era'bly at a temperature of from about 800 to.,900 F., and being downwardly directed as. a flowing stream relative to the moving wire), The,function of the air-wipe is to thin down and smooth out the zinc coating on the substrate-wire to conserve zinc and to produce a more uniform and even coating on the wire. Some control of zinc weights'can be had by regulatingthegas pressure. The present invention. is well adapted for .the production of thin, uniform coating of zinc on wires.

The present invention is particularly well suited and adapted for use in the galvanizing of wire which may be conveniently completely moistened or immersed in the bath of flowing zinc during traversal through such bath, in a vertical direction as described hereinabove. If stripj(fl a t tened) materials are to be z'inc coated, it is preferred, to have such strips enter the molten zinc bath at an angle which is substantially parallel to the directionof zinc flow so that the molten zinc moves easily and generally equally across each of the opposed faces of the strip member.

Referring to FIG. 1, there is seen an embodiment of apparatus suitable for galvanizing a filament of galvanizable iron material in accordance with the teachingsof the present invention, such apparatus being herein designated in its entirety by the numeral 10. The apparatus 10 employs a generally gas tight vessel herein designated in its entirety by the numeral 11 which is equipped with a filament entry port 12 and a filament exit port 13. The entry port 12 is located in a lateral side of the vessel 11, while the exit port 13 is located in a top portion of the vessel 11.

A conduit 14 is connected with the vessel 11 andis adapted to supply to the vessel interior a substantially oxygen freegas from a gas source (not shown).

Apparatus 10 includes two pulley means 16 and 17. Pulley 16 is journalled for rotational movements on a shaft 18 inside the vessel 11. Pulley 17 is journalled for rotational movements on a shaft 19 outside and above the vessel 11. Pulleys 1'6 and 17 are in an aligned, vertical relationship as respects the circumferential edge portions of each pulley 16 and 17 so as to adapt the pulleys 16- and 17 in combination to move a filament 21 vertically from pulley 16 to pulley 17 about the circumferential edge portions of the respective pulleys 16 and 17 with the filament passing through the filament entry port 11 and the filament exit port 13.

A reservoir 22 adapted for holding molten zinc 23 is provided within the vessel 11. The reservoir 22 has a spigot 24 at a bottom side thereof and a level regulating overflow pipe 26 at a top side thereof. A trough means 27 is located below but in proximity to the reservoir 22. The trough 27 is adapted to receive molten zinc discharged from the spigot 24 and from the overflow pipe 26.

The relationship between the trough 27 and the spigot 24 is such that an aperture 28 is defined spatially therebetween through which a substantially uniform stream 29 of molten zinc is adapted to flow when reservoir 22 is filled to the overflow pipe 26 with molten zinc 23. Through this aperture 28, as the stream 29 passes therethrough, filament 21 extends and moves vertically concurrently.

A tank 31 here shown lined refractory brie-ks or the like, is positioned spatially below but in proximity to the trough 27. The tank 31 is adapted to receive molten zinc discharged from the trough 27. The tank 31 includes heating means, such as electric heating coil 32 for heating and maintaining zinc 33 in tank 31 in a molten state. Suitable temperature regulating means (not shown) is provided. One presently preferred size for tank 31 is in the range of from about 20 to 40 gallons.

A conduit 34 extends from molten zinc 33 in a tank 31 upwardly and into molten zinc 23 in reservoir 22. An impeller 36 at the lower end of conduit 34 is provided to permit the pumping of molten zinc from tank 31 upwardly through conduit 34 and into the reservoir 23. The impeller 36 is mounted at the lower end of a shaft 37 which extends upwardly through conduit 34 through a shaft seal 38 through the upper wall of the vessel 11 to an electric motor drive means 39. As the impeller 36 revolves in response to rotational movements imparted thereto from the electric motor 39, the zinc in the reservoir 22 is maintained at a level in reservoir 22 adajacent the over-flow pipe 26. By this means, a relatively constant stream of molten zinc issues from the spigot 24 during operation of the apparatus 10.

Before entering apparatus 10, filament 21 is conveniently and conventionally subjected, as desired, to a series of preliminary processing steps. Thus, from a reel 41 of wire or the like, the filament 21 is drawn. Filament 21 is typically first subjected to a degreasing operation 42 followed by an acid pickling operation 43 which in turn is succeeded by a water rinsing operation 44. Optionally, following the rinsing operation, one can subject the filament 21 to a fluxing operation 45.

During the transport of the filament 21 through such preliminary operations, appropriate guide means including pulleys and the like, are provided, such as pulley 46. Following the various preliminary operations and before a filament 21 is introduced into the apparatus 10, it is subjected to a drying operation 47. Such degreasing, acid pickling, rinsing, fluxing and drying operations form no part of this invention and any convenient such operation or .technique may be employed as those skilled in the art will appreciate, as a preliminary to the galvanizing operation and technique provided by the teachings of the present invention.

Filament 48 passes through stream 54 after passing through the flowing stream 29. The resulting coated filament 48 exits from the vessel 11, moves over pulley 17 and onto a take-up reel 49. Take-up reel 49 is adjacent the outside pulley 17, conveniently. Take-up reel 49 is conveniently and preferably driven by a drive means which can comprise an electric motor 50 suitably interconnected with the shaft on which the take-up reel 49 is mounted, as those skilled in the art will appreciate.

Along the vertical path of coated filament 48 within a vessel 11, is located a gas-wiping assembly herein designated in its entirety by the numeral 52. Gas-wiping assembly 52 is located generally between the exit port 13 and the aperture 28 and assembly 52 is adapted to apply downwardly about the outside surfaces of the filament 48, a gas jet or stream of substantially oxygen free gas, in accordance with the process functionality hereinabove explained.

Positioned over exit port 13 is a nozzle 53 which is adapted to apply a stream 54 of water transversely across the filament 48 as such moves therethrough during operation of the apparatus 10. The temperature of the water, the size of the water stream and the rate of movement of the filament 48 are such that the zinc coating on filament 48 solidifies before the filament 48 traverses through the stream 54. The stream 54 is collected in a basin 56, or the like, for subsequent disposition, reuse, or the like, as desired. The nozzle 53 is located in suitable proximity to exit port 13 so that the filament 48 enters the stream of water 54 before the filament 48 has had any substantial exposure to atmospheric air or the like which contains oxygen. Usually, a single stream of water from a nozzle 54 is sufficient to accomplish the desired solidification of the zinc coating on the filament 48.

In order to provide convenient access to the interior of the vessel 11 in apparatus 10, convenient entry ports are provided. In the embodiment shown, two such ports 57 and 58 are shown although others may be provided as desired and as those skilled in the art will appreciate. Each port 57 and 58 is provided with a sealing door. The door itself comprises a panel of rectangular or circular or similar configuration which has about its outer perimeter a downturned flange. This flange is adapted to mate and engage with a trough circumferentially extending about the mouth of the opening 57 or 58 into the interior of vessel 11. Each such trough is filled with an inert material such as sand or the like. When the door is impressed against the opening, the flange imbeds itself in the sand thereby to achieve a seal.

Those skilled in the art will appreciate that the apparatus 10 may include a plurality of reservoirs 22 which are each fed from a common tank 31. In such an embodiment, the conduit 34 interconnects with a transversely extending conduit 59, and the conduit 59 is, in turn, interconnected with appropriately sized conduits 61 so as to provide a continuous stream of molten zinc, as desired, to each reservoir 22.

, EMBODIMENTS The present invention is illustrated by reference to the following examples. Those skilled in the art will appreciate that other and further embodiments and examples are obvious and within the spirit and scope of this invention from the teachings of the present examples taken with the accompanying specification and drawings. All parts are parts by weight unless otherwise indicated.

Other and further embodiments and modifications will be apparent to those skilled in the art from a reading of the present specification and drawings and no undue limitations are to be drawn therefrom.

EXAMPLE 1 Using apparatus generally of the type as shown in FIG. 1, but without the gas wiping assembly 52, a steel wire is subjected to a galvanizing operation in accordance with the teachings of this invention. As the inert gas used in the apparatus, natural gas is employed. The apparatus is first purged with natural gas before the hot melt galvanizing operation is begun to remove substantially all atmospheric air from the interior of the apparatus after which the natural gas pressure is maintained in the apparatus somewhat above atmospheric pressure, as demonstrated by a vigorous flow of natural gas from both the entry port 12 and the exit port 13. The wire used is subjected to a preliminary degreasing operation through soaking the entire reel in methanol after which the wire is dried substantially completely in an oven at 350 F. Thereafter, wire from the reel is threaded and drawn through the apparatus shown in FIG. 1 at the rate of about 20 feet per minute. The molten zinc bath is maintained at a temperature in the range of from about 830 to 870 F. The stream of hot, melted zinc emerges from an orifice which is about /4 in diameter. 7

Although the zinc is melted before the natural gas atmosphere in the apparatus is generated, the spout 24 is not opened until after the natural gas atmosphere is created, so that during the galvanizing operation only fresh molten zinc contacts the wire. While the wire passes through such stream of molten zinc and is subjected to the subsequent quenching operation, it contacts no solid physical object until it reaches a take up pulley and take up reel. Slightly above exit port 13 is a water stream which passes horizontally from a nozzle and through which the zinc coated wire passes as it emerges from exit port 13. The zinc coated on the wire is cooled to a temperature below about 780 F. as shown by the fact that only solid zinc exists on the wire after passage through the water stream. The coated wire displays what appears to be a uniform thin coating of zinc. The natural gas may be ignited and burned as it exits from ports 12 and 13.

EXAMPLE 2 Using apparatus generally of the type as shown in FIG. 1, but without the gas wiping assembly 52, a steel wire is subjected to a galvanizing operation in accordance with the teachings of .this invention. As the inert gas used in the apparatus, nitrogen is employed. The apparatus is first purged with nitrogen before the hot melt galvanizing operation is begun to remove substantially all atmospheric air from the interior of the apparatus after which the nitrogen pressure is maintained in the apparatus somewhat above atmospheric pressure, as demonstrated by a vigorous flow of nitrogen from both the entry port 12 and-the exit port 13. The wire used is subjected to a preliminary degreasing operation through soaking the entire reel in methanol after which the wire is dried substantially completely in an oven at 350 F. Thereafter, wire from the reel is threaded and drawn through the apparatus shown in FIG. lat the rate of about 20 feet per minuteJThe molten zinc bath is maintained at a temperature in the range of from about 830 to 870 F. The stream of hot, melted zinc emerges from an orifice which is about in diameter.

Although the zinc is melted before the nitrogen atmosphere in the apparatus is generated, the spout 24 is not opened until after the nitrogen atmosphere is created, so that during the galvanizing operation only fresh molten zinc contacts the wire. While the wire passes through such stream of molten zinc and is subjected to the subsequent quenching operation, it contacts no solid physical object until it reaches a take-up pulley and take-up reel. Slightly above exit port 13 is a water stream which passes horizontally from a nozzle and through which the zinc coated wire .passes as it emerges from exit port 13. The zinc coated on the wire is cooled to a temperature below about 780 F. as shown by the fact that only solid zinc exists on the wire after passage through the water stream. The coated wire displays what appears to be a uniform thin coating of zinc.

What is claimed is:

1. In an improved process for galvanizing a galvanizable metallic material in a wire-like form, the steps comprising:

(A) passing such wire-like form vertically upwardly through a generally transversely flowing stream of molten zinc while maintaining said zinc and said wirelike form in a substantially oxygen free atmosphere, and thereafter,

(B) maintaining the so-coated wire-like form in said vertical position in said atmosphere until the resulting coating of zinc on said wire-like form has solidified, said so -coated wire being further maintained in said atmosphere with such resulting zinc coating free from contact with solid objects until after solidification thereof.

2. The process of claim 1, wherein, after passing through said flowing stream, the resulting so-coated wire-like form while in said vertical position and in said oxygen-free atmosphere is then passed upwardly through a water bath,

the temperature of said bath and the residence time of such so-coated wire-like form in said bath being such that the resulting coating of zinc on said wire-like form has cooled and set.

3. The process of claim 2, wherein, said water bath flows in a direction generally transversely to said wirelike form. r

4. The process of claim 1, wherein, said flowing stream of molten zinc is not more than about two inches in vertical thickness at the point where said wire-like form passes therethrough.

5. The process of claim 1, wherein, said wire vertically travels through said flowing stream at a rate of from about 10 to 30 feet per minute.

6. The process of claim 1, wherein, said flowing stream of molten zinc is maintained at a substantially constant temperature in the range of from about 800 to 900 F. whereby said stream has a substantially constant viscosity.

7. The process of claim 1, wherein, said so-coated and cooled wire has a zinc coating of from about 0.05 to 0.0001 inch.

8. The process of claim 1, wherein, said so-coated and cooled wire has a coating weight of not more than about 2 ounces per square foot of coated wire surface.

9. The process of claim 1, wherein, after said passing, said so-coated, vertical wire passes upwardly through a downwardly directed, substantially oxygen-free gas stream before the resulting coating of zinc on said wire solidifies.

10. A method for galvanizing a wire galvanizable me-' tallic material in a wire-like form comprising the steps of continuously and sequentially:

(A) passing said wire-like form through a pickling bath to remove substantially all scale therefrom,

(B) passing said so-pickled wire-like form through a drying zone wherein said so-pickled wire-like form is subjected to elevated temperatures for a'time sufficient to substantially completely dry said wire-like form,

(C) passing said so-dried wire-like form upwardly through a generally transversely flowing stream of molten 'z'inc which simultaneously (1) maintains said wire-like form in a vertical "position, and

v (2) maintains said molten zinc and said wire-like form in a substantially oxygen free atmosphere to coat such wire-like form with a layer of zinc,

and

(D) passing said so-coated wire-like form while in said vertical position and while still in said substantially oxygen free atmosphere upwardly through a water bath, the temperature of said bath and the residence time of such wire-like form in said bath being such that such zinc coating is cooled below its melting point, said so-coated wire being maintained in said atmosphere with such zinc coating free from contact with solid objects until after solidification thereof.

11. The process of claim 10, wherein said water bath flows in a direction generally transversely'to said-wire. 12.-The' process of claim 10,-wherein;said flowing stream of molten- -,zinc" is not more thanabouttwo inches in vertical thickness at the point where said wire passes therethrough. i. 4 13. The process of claim 10, wherein saidqwire-"vertically travels through said flowing stream atarate'offrom about lO'to 30 feet per minute.

14. The process of claim 10 wherein. saidso-coated and cooled wire has a zinc coating weight ofgnot "more thanabout '2 ouncesper square foot of coated filament surface; v 1" v 1'5.-='The process of claim 10, wherein isaidviflowing stream is maintained 'at' a substantially constant temperatur'ein therange of from about: 8-30 to 870 16. The process of claim 10, wherein after passing through said generally transversely flowing streamof? molten zinc; 'sai'd wire is; passedvertically through at least one additionalsuch flowing stream-of molten zinc in suchsubstantially oxygen free atmosphere before the resultinglsuc filament is passed through said waterbath;

;a:Re feremies Cited; V '"UN ITED' STATES PATENTS D RU: Primary Eiraminer M. BALL, Assistant Examiner 

